The popularity of four wheel drive vehicles continues to drive consumer purchases. At one time, four wheel drive was generally limited to foreign passenger cars and low gear operation in trucks. Adaptive and full time four wheel drive systems are now available across passenger car, truck and SUV markets. Accompanying the expansion of four wheel drive applications has been extensive development of the electronic sensors and controls of such systems. This, too, has furthered the utility and appeal of four wheel drive vehicles.
The features and benefits of four wheel drive vehicles frequently suppress consideration of less positive aspects, particularly the mechanical complexity of such systems, their added weight and thus the negative impact on vehicle fuel economy. The unidirectional trend of fuel costs suggests that mechanical and electronic systems that provide four wheel drive function with reduced complexity and weight is therefore a desirable goal. The present invention is directed to such a vehicle driveline configuration.